Toyota magnetic vss sensor help

[Toybox]

Its a 1996 Toyota Hilux, the equivalent of a 4Runner in the rest of the world.

Its a cable driven speedo, so I've glued the reed switch onto the back of the speedo, behind the circular magnet.

The car has had an engine and gearbox conversion so the ECU's for engine and gearbox are aftermarket.

[Toybox]

I got the instructions off a link on this forum. I'll see if I can scratch it up.

[Toybox]

Here you go:

Adding a VSS output to a Mechanical Speedo (reed switch)

[ECONORAM]

Originally Posted by meelis11

I dont know what mpguino you have but it normally expects VSS input to be pulsed 12V.

If yours is 5V max, then you can probably change resistor(s) in VSS input (probably around 50K) to smaller value resistors (5K-10k maybe?)
My point is that instead amplify 5V to 12V you change resistors between VSS input pin and microprocessor (input to atmega can be 0-5V)

I tried that myself, and it didn't work...so I made a corroplast disk with holes, clamped it to my driveshaft, and wired in a 12v gauge bulb and IR sensor to read the light pulses. I'm on my third disk already, so the step up voltage sounds like a much better idea...

[meelis11]

Originally Posted by ECONORAM

I tried that myself, and it didn't work...so I made a corroplast disk with holes, clamped it to my driveshaft, and wired in a 12v gauge bulb and IR sensor to read the light pulses. I'm on my third disk already, so the step up voltage sounds like a much better idea...

Newer schematics seems to use voltage divider in atmega VSS pin. You can try to unsolder resistor between VSS input and ground pin (if you have 2 resistors in VSS pin - keep this one - between mpguino VSS input pin and atmega pin).

Edit:
if your mpguino is based on this schematic, then voltage divider is made using R3 and R6 - remove R6 (then all voltage reaches to pin 23, otherwise half of voltage)
http://opengauge.googlecode.com/svn/...no/mpguino.png

Let me know if it helps

Meelis

[williamscao]

The automatic gearbox uses a 2 wire magnetic sensor and the 4 bolts on the propshaft as the trigger.

[Toybox]

The reed switch and little circuit seem to be working well enough. Not perfectly stable, a km/h or 2 variation as I drive, but that may be due to a work speedo gear/cable as the speedo needle isn't stable either.

It'll do for the moment I'm sure.

[ECONORAM]

Originally Posted by meelis11

Newer schematics seems to use voltage divider in atmega VSS pin. You can try to unsolder resistor between VSS input sng ground pin (if you have 2 resistors in VSS pin - keep this one - between mpguino VSS input pin and atmega pin).

Edit:
if your mpguino is based on this schematic, then I voltage divider is made using R3 and R6 - remove R6 (then all voltage reaches to pin 23, otherwise half of voltage)
http://opengauge.googlecode.com/svn/...no/mpguino.png

Let me know if it helps

Meelis

Thank you sir. I think that is what my schematic/MPGuino is. I do have v1.3, and I pretty sure I ordered it (pre-built) in early 2010. But I'll have to scratch my head a bit to figure out which resistor is "R6."
[edit] Found a link here on ecomodder! http://ecomodder.com/forum/showthrea...-r6-17072.html

[ECONORAM]

Well, that didn't do it. Not sure why. I tried soldering in a 100 ohm, then went with a straight wire. Still no joy. Better yet, when I went to remove the 100 ohm resistor I broke the wire for the resistor on the circuit board; that took some work to solder in a repair... So I made a new speed sensor disk, fixed my other wires only to discover the bulb had burned out. Sigh.

[edit] and that was only the beginning. It seems some of the insulation wore off near one of the brackets, which caused a short and blew the fuse. So, after replacing all the wiring, the speed disk, and the fuse I discover I still have no indication. Must have smoked something in the MPGuino...